... bits, rock bits, tricone bits, single cone bits, steel tooth bits, insert tooth bits, roller bits, drill bits, drilling tools etc. we ... welling drilling and so on.3.It is almost suitable for hard rocks, such as limestone, dolomite, chert, firm sandstone, and firm ... ,,617,627,637,737512,522,532,612,622,632,732Bearing Type:HJ(metal sealed journal bearing) HA (rubber sealed journal bearingNo ...